If you are running Apache there is nothing to worry about, these
requests are part of the Code Red
Worm designed to search out vulnerable IIS servers
running on Windows. You can quite happily ignore these
requests

Other common requests

Other common log entries you might see include:

Requests for robots.txt in the root directory. These
requests are normally automatically made by robots which will analyse
the contents of this file to see what files and directories they are
not allowed to access. The format of the robots.txt file is given
in the HTML 4 Specification.

Requests for favicon.ico in various directories
(first seen in April 1999). Microsoft Internet Explorer version 5 and
above can display a site-defined icon when a site's URL is displayed
in a favourites list. This icon is obtained by asking the site for
favicon.ico. If the URL contains slash characters
(normally used to represent a directory hierarchy), MSIE 5 will
request "favicon.ico" in each parent directory until it finds one or
reaches the root. The format of the favicon.ico file is
the Microsoft icon format. To see this 'feature' in action, bookmark
this page using MSIE.

Requests for cmd.exe in various directories. These are
usually attempts to exploit various security
vulnerabilities that affect Microsoft IIS servers.